Transplanted neurons can "get infected" with parkinsonism
Brain cell transplantation cannot serve as a panacea for Parkinson's disease. Postmortem autopsies of several patients showed that the disease can also affect transplanted cells, the journal Nature Medicine reports.
American and Swedish scientists have studied the brain structure of patients with Parkinson's disease who underwent brain tissue transplantation of aborted embryos. Parkinson's disease is accompanied by the death of cells that produce the neurotransmitter dopamine. The transplants were supposed to replace dead cells in the brain of patients and restore the production of the necessary substance.
Jeffrey H. Kordower and his colleagues from Rush University Medical Center (Chicago) studied the brain of a woman who died 14 years after a brain tissue transplant. According to their data, after the transplantation carried out in 1993, the patient's condition improved. However, in 2004, the disease began to progress again, and in 2007 the patient died. In turn, Swedish scientists from the Wallenberg Neurological Center examined the brains of two patients who died 11 and 16 years after transplantation.
According to the researchers, all three patients had signs indicating that the grafts were affected by Parkinson's disease. In particular, some of the transplanted neurons contained the so–called Levi corpuscles - clusters of alpha-synuclein protein characteristic of this disease.
Meanwhile, it is known that Levi's corpuscles are usually not formed in cells whose "age" is younger than 40 years, and their formation in cells transplanted from 11 to 16 years ago cannot be explained by natural processes. It is possible that transplanted healthy cells are infected from patients with the help of an abnormal alpha-synuclein protein – that is, in Parkinson's disease, a process similar to prion diseases (in particular, mad cow disease) is observed, scientists suggested. According to another theory, graft damage is associated with immune reactions and the development of inflammation.
It is not yet known whether the disease will affect patients' own stem cells (for example, derived from skin cells). Further in-depth research is needed to answer this question, the scientists note.
Source: Transplanted cells could 'catch' Parkinson's – New Scientist, 07.04.2008
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08.04.2008